[CIG-SEISMO] Problem with external velocity model

[Fehr, Moritz]

Hi,
I have some issues using an external velocity model with ”low“ velocities. The model size is 3 x 3 x 2.52 km and the mesh size is 40 m in all directions. The velocity model is discretized with 40m as well.
If  I  use my initial velocity model with minimum velocities Vp = 2263 m/s and Vs = 1307 m/s the simulation works fine. In the next step I wanted to implement a low velocity patch within the initial velocity model (see: v_model_patch.png) to investigate the influence of the low velocity body. The minimum velocities are Vp = 955 m/s and Vs = 555 m/s (blue). The problem is that SPECFEM do not detect these low velocities (see output_solver.txt) and the simulation provides the same results as the initial simulation. I also tried different mesh sizes and velocity model spacing but the problem still remains. Do anybody have an idea about the origin of that issue?

Thanks
Moritz

PS: I am using SPECFEM3D Cartesian (Version 3.0) with two GPUs  (Tesla K40m) and 28 CPUs.



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